Decimal to fraction won't work for negative numbers

Question

I have this script that coverts decimals to fractions:

function toFraction($number){ 
    $numerator = 1; 
    $denominator = 0; 
    for(; $numerator < 1000; $numerator++){ 
        $temp = $numerator / $number; 
        if(ceil($temp) - $temp == 0){ 
            $denominator = $temp; 
            break; 
        } 
    } 
    return ($denominator > 0) ? $numerator . '/' . $denominator : false; 
}

However, after some testing, it seems like it does not work for negative decimals. Why is this? Also, what is the solution to allow it to work with negative decimals?

Answer 1

It probably doesn't work because of the way your logic is set up in your for loop. What I would do is do a check to see if the number is negative at the beginning of your function. If it is, I would set a flag to remind the function that it was originally negative, and then I would flip the sign of the incoming $number. Then, right before returning, I would check to see if my flag was set, and if it was, I would simply invert the return value.

function toFraction($number){ 
    if ($number < 0) {
        $number *= -1;
        $isInverted = true;
    }

    $numerator = 1; 
    $denominator = 0; 
    for(; $numerator < 1000; $numerator++){ 
        $temp = $numerator / $number; 
        if(ceil($temp) - $temp == 0){ 
            $denominator = $temp; 
            break; 
        } 
    } 

    if ($isInverted)
        $numerator *= -1;

    return ($denominator > 0) ? $numerator . '/' . $denominator : false; 
}